Print Setup Manager
This plugin shows you all the print setups in a table, making it easier to manage print setups, especially when there are lots of them.
You can edit a print setup directly in the table and you can even duplicate it.
Note: For editing a print setup you should select a print driver. If the paper size in a print setup is not defined in the selected printer, that print setup won't be added to the mentioned table. You should first define the paper size in the printer preferences to access that print setup.